package recharge

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"
	"time"

	kratoserrors "github.com/go-kratos/kratos/v3/errors"

	bizpayment "kra/internal/biz/payment"
)

const BusinessType = "live_recharge"

var (
	ErrNotFound          = kratoserrors.NotFound("RECHARGE_ORDER_NOT_FOUND", "recharge order not found")
	ErrInvalid           = kratoserrors.BadRequest("RECHARGE_INVALID", "invalid recharge data")
	ErrRefundUnsupported = kratoserrors.BadRequest("RECHARGE_REFUND_UNSUPPORTED", "recharge refunds require manual balance reconciliation")
)

type Plan struct {
	ID                    uint
	Sort                  int
	Diamonds, AmountCents int64
	Enabled               bool
}

// Order owns recharge facts. Payment state comes from KRA's payment order.
type Order struct {
	ID                                             uint
	OrderNo                                        string
	UserID                                         uint
	Username, Nickname                             string
	Diamonds, AmountCents                          int64
	Provider, ProviderTradeNo                      string
	PaymentStatus, FulfillmentStatus, RefundStatus string
	CreatedAt                                      time.Time
	CreditedAt                                     *time.Time
}

type Checkout struct {
	Provider  string
	NotifyURL string
	ReturnURL string
	ClientIP  string
	UserAgent string
	DeviceID  string
	Extra     map[string]any
}

type Filter struct {
	OrderNo, UserKeyword, PaymentStatus, Provider string
	CreatedAt                                     []time.Time
}

type ListOptions struct {
	Offset, Limit int
	OrderBy       string
}

type Summary struct{ Count, PaidCount, AmountCents int64 }

type Repo interface {
	Plans(context.Context) ([]*Plan, error)
	SavePlans(context.Context, []*Plan) error
	List(context.Context, Filter, ListOptions) ([]*Order, int64, *Summary, error)
	Get(context.Context, string) (*Order, error)
	Create(context.Context, uint, uint) (*Order, error)
	MarkPaid(context.Context, string) (*Order, error)
}

type Usecase struct {
	repo     Repo
	payments *bizpayment.PaymentUsecase
}

func NewUsecase(repo Repo, payments *bizpayment.PaymentUsecase) (*Usecase, error) {
	uc := &Usecase{repo: repo, payments: payments}
	if payments == nil {
		return nil, fmt.Errorf("充值支付服务未接入")
	}
	if err := payments.RegisterBusinessModule(uc); err != nil {
		return nil, err
	}
	return uc, nil
}

func (uc *Usecase) Plans(ctx context.Context) ([]*Plan, error) { return uc.repo.Plans(ctx) }

func (uc *Usecase) SavePlans(ctx context.Context, plans []*Plan) error {
	if len(plans) < 1 || len(plans) > 8 {
		return ErrInvalid
	}
	for i, p := range plans {
		if p == nil || p.Diamonds < 1 || p.Diamonds > 99999 || p.AmountCents < 1 || p.AmountCents > 999900 {
			return ErrInvalid
		}
		if p.Sort == 0 {
			p.Sort = i + 1
		}
		p.Enabled = true
	}
	return uc.repo.SavePlans(ctx, plans)
}

func (uc *Usecase) List(ctx context.Context, f Filter, o ListOptions) ([]*Order, int64, *Summary, error) {
	if o.Limit < 1 || o.Limit > 100 {
		o.Limit = 10
	}
	return uc.repo.List(ctx, f, o)
}

func (uc *Usecase) Get(ctx context.Context, no string) (*Order, error) {
	if strings.TrimSpace(no) == "" {
		return nil, ErrNotFound
	}
	return uc.repo.Get(ctx, no)
}

func (uc *Usecase) Create(ctx context.Context, userID, planID uint, checkout Checkout) (*Order, *bizpayment.PaymentResult, error) {
	checkout.Provider = strings.TrimSpace(checkout.Provider)
	if userID == 0 || planID == 0 || checkout.Provider == "" || checkout.Provider == bizpayment.PaymentInternal || !bizpayment.IsSupportedPaymentProvider(checkout.Provider) {
		return nil, nil, ErrInvalid
	}
	order, err := uc.repo.Create(ctx, userID, planID)
	if err != nil {
		return nil, nil, err
	}
	extra := make(map[string]any, len(checkout.Extra)+2)
	for key, value := range checkout.Extra {
		extra[key] = value
	}
	extra["userId"] = order.UserID
	extra["diamonds"] = order.Diamonds
	result, err := uc.payments.Create(ctx, &bizpayment.PaymentRequest{
		Provider: checkout.Provider, TradeNo: order.OrderNo,
		BusinessType: BusinessType, BusinessID: order.OrderNo,
		NotifyURL: checkout.NotifyURL, ReturnURL: checkout.ReturnURL,
		ClientIP: checkout.ClientIP, UserAgent: checkout.UserAgent, DeviceID: checkout.DeviceID,
		Extra: extra,
	})
	if err != nil {
		return order, nil, err
	}
	refreshed, err := uc.repo.Get(ctx, order.OrderNo)
	if err != nil {
		return nil, nil, err
	}
	return refreshed, result, nil
}

func (uc *Usecase) Type() string { return BusinessType }

func (uc *Usecase) PreparePayment(ctx context.Context, provider, tradeNo, businessID string) (*bizpayment.PaymentIntent, error) {
	if strings.TrimSpace(provider) == "" || tradeNo == "" || businessID != tradeNo {
		return nil, bizpayment.ErrPaymentOrderConflict
	}
	order, err := uc.repo.Get(ctx, businessID)
	if err != nil {
		return nil, err
	}
	if order.OrderNo != tradeNo || order.CreditedAt != nil {
		return nil, bizpayment.ErrPaymentOrderConflict
	}
	extra, err := json.Marshal(map[string]any{"userId": order.UserID, "diamonds": order.Diamonds})
	if err != nil {
		return nil, err
	}
	return &bizpayment.PaymentIntent{
		Provider: provider, TradeNo: tradeNo, BusinessType: BusinessType, BusinessID: businessID,
		Subject: fmt.Sprintf("充值 %d 钻石", order.Diamonds), Amount: order.AmountCents,
		OriginalAmount: order.AmountCents, Currency: "CNY", PaymentMode: bizpayment.PaymentModeExternal,
		Extra: extra,
	}, nil
}

func (uc *Usecase) Fulfill(ctx context.Context, confirmation *bizpayment.PaymentConfirmation) error {
	if confirmation == nil || confirmation.BusinessType != BusinessType || confirmation.BusinessID == "" || confirmation.TradeNo != confirmation.BusinessID || !strings.EqualFold(confirmation.Currency, "CNY") {
		return ErrInvalid
	}
	order, err := uc.repo.Get(ctx, confirmation.BusinessID)
	if err != nil {
		return err
	}
	if order.AmountCents != confirmation.Amount {
		return bizpayment.ErrPaymentOrderConflict
	}
	_, err = uc.repo.MarkPaid(ctx, order.OrderNo)
	return err
}

// Refunds stay disabled until diamonds can be reserved across an async refund.
func (uc *Usecase) AuthorizeRefund(context.Context, *bizpayment.PaymentOrder, int64) error {
	return ErrRefundUnsupported
}